The following techniques may be employed to impart finite circulation (or loading) values to blade tips of marine propellers used to power ships:
(a) having the propellers operate inside a nozzle or in any closed duct having a circular cross section which is coaxial with the propeller, and PA1 (b) adding closing plates to the tip sections of the propeller blades in a manner similar to that described in such U.S. patents as No. 28,688 (Porter), No. 170,937 (Cook), No. 652,123 (Lavigne), No. 675,477 (Hall) and No. 695,389 (Hammond).
The noted closing plates can be linked to form a concentric ring with the propeller.